<?php
interface Color
{
    /** @return void */
    public function fill();
}

class Red implements Color
{
    public function fill()
    {
        echo "Red\r\n";
    }
}

class Green implements Color
{
    public function fill()
    {
        echo "Green\r\n";
    }
}

class Blue implements Color
{
    public function fill()
    {
        echo "Blue\r\n";
    }
}
